26 results on '"Olivia J. Maselli"'
Search Results
2. Sea ice and pollution-modulated changes in Greenland ice core methanesulfonate and bromine
- Author
-
Daniel R. Pasteris, Olivia J. Maselli, Michael Sigl, Lawrence Layman, Nathan Chellman, Rachael H. Rhodes, Joseph R. McConnell, Eric S. Saltzman, Mackenzie M. Grieman, Rhodes, Rachael [0000-0001-7511-1969], and Apollo - University of Cambridge Repository
- Subjects
010504 meteorology & atmospheric sciences ,sub-01 ,lcsh:Environmental protection ,Stratigraphy ,Ice stream ,Greenland ice sheet ,3705 Geology ,F800 ,Antarctic sea ice ,010501 environmental sciences ,01 natural sciences ,lcsh:Environmental pollution ,Sea ice ,Cryosphere ,lcsh:TD169-171.8 ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Paleontology ,37 Earth Sciences ,3709 Physical Geography and Environmental Geoscience ,Arctic ice pack ,Oceanography ,13. Climate action ,lcsh:TD172-193.5 ,Sea ice thickness ,Ice sheet ,Geology - Abstract
Reconstruction of past changes in Arctic sea ice extent may be critical for understanding its future evolution. Methanesulfonate (MSA) and bromine concentrations preserved in ice cores have both been proposed as indicators of past sea ice conditions. In this study, two ice cores from central and north-eastern Greenland were analysed at sub-annual resolution for MSA (CH3SO3H) and bromine, covering the time period 1750–2010. We examine correlations between ice core MSA and the HadISST1 ICE sea ice dataset and consult back trajectories to infer the likely source regions. A strong correlation between the low-frequency MSA and bromine records during pre-industrial times indicates that both chemical species are likely linked to processes occurring on or near sea ice in the same source regions. The positive correlation between ice core MSA and bromine persists until the mid-20th century, when the acidity of Greenland ice begins to increase markedly due to increased fossil fuel emissions. After that time, MSA levels decrease as a result of declining sea ice extent but bromine levels increase. We consider several possible explanations and ultimately suggest that increased acidity, specifically nitric acid, of snow on sea ice stimulates the release of reactive Br from sea ice, resulting in increased transport and deposition on the Greenland ice sheet.
- Published
- 2017
3. Local artifacts in ice core methane records caused by layered bubble trapping and in situ production: a multi-site investigation
- Author
-
Michael Sigl, J. S. Edwards, Thomas Blunier, Jérôme Chappellaz, Xavier Faïn, Edward J. Brook, Christo Buizert, Olivia J. Maselli, Joseph R. McConnell, Rachael H. Rhodes, Johannes Freitag, College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Division of Hydrologic Sciences, Desert Research Institute (DRI), Paul Scherrer Institute (PSI), Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Université Grenoble Alpes (UGA), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Rhodes, Rachael [0000-0001-7511-1969], and Apollo - University of Cambridge Repository
- Subjects
atmospheric chemistry ,010504 meteorology & atmospheric sciences ,sub-01 ,Stratigraphy ,Bubble ,lcsh:Environmental protection ,Greenland ,Mineralogy ,firn ,F800 ,010502 geochemistry & geophysics ,01 natural sciences ,Methane ,chemistry.chemical_compound ,Arctic ,Ice core ,lcsh:Environmental pollution ,lcsh:TD169-171.8 ,Density contrast ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,amplitude ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,filter ,geography.geographical_feature_category ,heterogeneous medium ,methane ,Firn ,diffusion ,Paleontology ,artifact ,ice sheet ,Trace gas ,chemistry ,13. Climate action ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,Climatology ,atmosphere ,lcsh:TD172-193.5 ,Polar ,Environmental science ,Ice sheet ,accumulation ,ice core - Abstract
Advances in trace gas analysis allow localised, non-atmospheric features to be resolved in ice cores, superimposed on the coherent atmospheric signal. These high-frequency signals could not have survived the low-pass filter effect that gas diffusion in the firn exerts on the atmospheric history and therefore do not result from changes in the atmospheric composition at the ice sheet surface. Using continuous methane (CH4) records obtained from five polar ice cores, we characterise these non-atmospheric signals and explore their origin. Isolated samples, enriched in CH4 in the Tunu13 (Greenland) record are linked to the presence of melt layers. Melting can enrich the methane concentration due to a solubility effect, but we find that an additional in situ process is required to generate the full magnitude of these anomalies. Furthermore, in all the ice cores studied there is evidence of reproducible, decimetre-scale CH4 variability. Through a series of tests, we demonstrate that this is an artifact of layered bubble trapping in a heterogeneous-density firn column; we use the term “trapping signal” for this phenomenon. The peak-to-peak amplitude of the trapping signal is typically 5 ppb, but may exceed 40 ppb. Signal magnitude increases with atmospheric CH4 growth rate and seasonal density contrast, and decreases with accumulation rate. Significant annual periodicity is present in the CH4 variability of two Greenland ice cores, suggesting that layered gas trapping at these sites is controlled by regular, seasonal variations in the physical properties of the firn. Future analytical campaigns should anticipate high-frequency artifacts at high-melt ice core sites or during time periods with high atmospheric CH4 growth rate in order to avoid misinterpretation of such features as past changes in atmospheric composition.
- Published
- 2016
4. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)
- Author
-
Alfonso Saiz-Lopez, Diedrich Fritzsche, Andrea Spolaor, Joseph R. McConnell, Cristiano Varin, Gunnar Spreen, Torben Kirchgeorg, Paul Vallelonga, Olivia J. Maselli, and Thomas Opel
- Subjects
Arctic sea ice decline ,010504 meteorology & atmospheric sciences ,Antarctic sea ice ,010502 geochemistry & geophysics ,01 natural sciences ,Halogens ,Arctic ,Ice core ,Sea ice ,Cryosphere ,Settore CHIM/01 - Chimica Analitica ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,lcsh:GE1-350 ,Drift ice ,NORDIC SEAS ,geography ,geography.geographical_feature_category ,lcsh:QE1-996.5 ,BOUNDARY-LAYER ,WEDDELL SEA ,MASS-SPECTROMETRY ,RECORD ,Arctic ice pack ,lcsh:Geology ,ANTARCTICA ,CLIMATE ,IODINE EMISSIONS ,VARIABILITY ,BROMINE ,Oceanography ,MASS-SPECTROMETRY, IODINE EMISSIONS, BOUNDARY-LAYER, WEDDELL SEA, NORDIC SEAS, VARIABILITY, ANTARCTICA, BROMINE, CLIMATE, RECORD ,13. Climate action ,Ice-core ,Sea-ice ,Geology - Abstract
The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The chemistry of halogens bromine (Br) and iodine (I) is strongly active and influenced by sea ice dynamics, in terms of physical, chemical and biological process. Bromine reacts on the sea ice surface in autocatalyzing >bromine explosion> events, causing an enrichment of the Br/Na ratio and hence a bromine excess (Br) in snow compared to that in seawater. Iodine is suggested to be emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. The correlation coefficients obtained between Br and spring sea ice (r = 0.44) as well as between iodine and summer sea ice (r = 0.50) for the Laptev Sea suggest that these two halogens could become good candidates for extended reconstructions of past sea ice changes in the Arctic., This study contributes to the Eurasian Arctic Ice 4k project and was supported by the Deutsche Forschungs- gemeinschaft (grant OP 217/2-1 awarded to Thomas Opel). The drilling project on the Akademii Nauk ice cap was funded by the German Ministry of Education and Research (BMBF research project 03PL 027A). Analysis and interpretation of the Akademii Nauk ice core at the Desert Research Institute was funded by US National Science Foundation grant 1023672. The research leading to these results received funding from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement no. 610055. We thank the University of Bremen, supported by the State of Bremen; the German Aerospace Center, DLR; and the European Space Agency for the satellite BrO imagines. Opel)
- Published
- 2016
5. A horizontal ice core from Taylor Glacier, its implications for Antarctic climate history, and an improved Taylor Dome ice core time scale
- Author
-
Joseph R. McConnell, Jeffrey P. Severinghaus, Robert Mulvaney, Michael Sigl, Olivia J. Maselli, Eric J. Steig, Daniel Baggenstos, Benjamin Grente, and Jean-Robert Petit
- Subjects
010506 paleontology ,Atmospheric Science ,geography ,geography.geographical_feature_category ,Taylor Dome time scale ,010504 meteorology & atmospheric sciences ,Scale (ratio) ,Paleontology ,Glacier ,Taylor Glacier ,north-south synchonicity ,Oceanography ,deglaciation ,01 natural sciences ,Climate Action ,Dome (geology) ,Ice core ,Climatology ,Antarctic climate ,Deglaciation ,Geology ,horizontal ice core ,0105 earth and related environmental sciences - Abstract
Ice core records from Antarctica show mostly synchronous temperature variations during the last deglacial transition, an indication that the climate of the entire continent reacted as one unit to the global changes. However, a record from the Taylor Dome ice core in the Ross Sea sector of East Antarctica has been suggested to show a rapid warming, similar in style and synchronous with the Oldest Dryas—Bølling warming in Greenland. Since publication of the Taylor Dome record, a number of lines of evidence have suggested that this interpretation is incorrect and reflects errors in the underlying time scale. The issues raised regarding the dating of Taylor Dome currently linger unresolved, and the original time scale remains the de facto chronology. We present new water isotope and chemistry data from nearby Taylor Glacier to resolve the confusion surrounding the Taylor Dome time scale. We find that the Taylor Glacier record is incompatible with the original interpretation of the Taylor Dome ice core, showing that the warming in the area was gradual and started at ∼18 ka BP (before 1950) as seen in other East Antarctic ice cores. We build a consistent, up‐to‐date Taylor Dome chronology from 0 to 60 ka BP by combining new and old age markers based on synchronization to other ice core records. The most notable feature of the new TD2015 time scale is a gas age—ice age difference of up to 12,000 years during the Last Glacial Maximum, by far the largest ever observed.
- Published
- 2018
- Full Text
- View/download PDF
6. No Coincident Nitrate Enhancement Events in Polar Ice Cores Following the Largest Known Solar Storms
- Author
-
Nathan Chellman, Andrew D. Moy, Raimund Muscheler, Florian Mekhaldi, Monica M. Arienzo, Florian Adolphi, Joseph R. McConnell, Michael Sigl, Olivia J. Maselli, and CT Plummer
- Subjects
Solar storm of 1859 ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Solar energetic particles ,chemistry.chemical_element ,Storm ,Atmospheric sciences ,01 natural sciences ,Nitrogen ,Proxy (climate) ,chemistry.chemical_compound ,Geophysics ,chemistry ,Ice core ,Nitrate ,Space and Planetary Science ,Climatology ,0103 physical sciences ,Earth and Planetary Sciences (miscellaneous) ,Polar ,Environmental science ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Knowledge on the occurrence rate of extreme solar storms is strongly limited by the relatively recent advent of satellite monitoring of the Sun. To extend our perspective of solar storms prior to the satellite era and because atmospheric ionization induced by solar energetic particles (SEPs) can lead to the production of odd nitrogen, nitrate spikes in ice cores have been tentatively used to document both the occurrence and intensity of past SEP events. However, the reliability of the use of nitrate in ice records as a proxy for SEP events is strongly debated. This is partly due to equivocal detection of nitrate spikes in single ice cores and possible alternative sources, such as biomass burning plumes. Here we present new continuous high-resolution measurements of nitrate and of the biomass burning species ammonium and black carbon, from several Antarctic and Greenland ice cores. We investigate periods covering the two largest known SEP events of 775 and 994 Common Era as well as the Carrington event and the hard SEP event of February 1956. We report no coincident nitrate spikes associated with any of these benchmark events. We also demonstrate the low reproducibility of the nitrate signal in multiple ice cores and confirm the significant relationship between biomass burning plumes and nitrate spikes in individual ice cores. In the light of these new data, there is no line of evidence that supports the hypothesis that ice cores preserve or document detectable amounts of nitrate produced by SEPs, even for the most extreme events known to date.
- Published
- 2017
7. Observing and modeling the influence of layering on bubble trapping in polar firn
- Author
-
Richard B. Alley, Rachael H. Rhodes, Joseph R. McConnell, Jinho Ahn, Jeffrey P. Severinghaus, Stephanie Gregory, Christo Buizert, Mary R. Albert, Edward J. Brook, Michael Sigl, Anais Orsi, Logan Mitchell, Olivia J. Maselli, John M. Fegyveresi, Daniel J. Breton, Daniel Baggenstos, College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Desert Research Institute (DRI), Laboratory of Radio- and Environmental Chemistry [Villigen], Paul Scherrer Institute (PSI), Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Atmospheric Science ,Bubble ,Antarctic ice sheet ,F800 ,firn ,Physical Geography and Environmental Geoscience ,Methane ,Atmospheric Sciences ,Physics::Geophysics ,layering ,chemistry.chemical_compound ,Ice core ,Earth and Planetary Sciences (miscellaneous) ,Meteorology & Atmospheric Sciences ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,Porosity ,Physics::Atmospheric and Oceanic Physics ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,methane ,firn density ,Firn ,Geophysics ,total air content ,Trace gas ,Climate Action ,chemistry ,13. Climate action ,Space and Planetary Science ,Climatology ,Layering ,ice core ,Geology - Abstract
International audience; Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.
- Published
- 2015
8. Timing and climate forcing of volcanic eruptions for the past 2,500 years
- Author
-
Robert Mulvaney, Nathan Chellman, Ulf Büntgen, Simon Schüpbach, Dorthe Dahl-Jensen, Olivia J. Maselli, Joseph R. McConnell, Bo Møllesøe Vinther, Francis Ludlow, Marc W. Caffee, Sepp Kipfstuhl, Thomas E. Woodruff, Conor Kostick, Jonathan R. Pilcher, Raimund Muscheler, Gill Plunkett, J. P. Steffensen, Kees C. Welten, Michael Sigl, Matthew W. Salzer, Hubertus Fischer, Florian Mekhaldi, Daniel R. Pasteris, Mai Winstrup, Buentgen, Ulf [0000-0002-3821-0818], and Apollo - University of Cambridge Repository
- Subjects
Time Factors ,Meteorology ,Climate ,Greenland ,Antarctic Regions ,Poison control ,Volcanic Eruptions ,Forcing (mathematics) ,Trees ,Latitude ,Disasters ,Ice core ,Tropical climate ,SDG 13 - Climate Action ,Carbon Radioisotopes ,History, Ancient ,Aerosols ,Radioisotopes ,Tropical Climate ,geography ,Multidisciplinary ,geography.geographical_feature_category ,Atmosphere ,Ice ,Radiometric Dating ,Temperature ,Northern Hemisphere ,Radiative forcing ,History, Medieval ,Europe ,Volcano ,13. Climate action ,Climatology ,Beryllium ,Seasons ,Americas ,Sulfur ,Geology - Abstract
Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.
- Published
- 2015
- Full Text
- View/download PDF
9. Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion
- Author
-
Joseph R. McConnell, Hans-F. Graf, Nels Iverson, Monica M. Arienzo, Gisela Winckler, Jihong Cole-Dai, Edward J. Brook, Jørgen Peder Steffensen, Gregor Knorr, Andrea Burke, Eric S. Saltzman, Robert Mulvaney, Nelia W. Dunbar, Tyler J. Fudge, Nathan Chellman, Peter Köhler, Kendrick C. Taylor, Kenneth C. McGwire, Christo Buizert, Jess F. Adkins, Jeffrey P. Severinghaus, Guillaume Paris, Mackenzie M. Grieman, Olivia J. Maselli, John F. Burkhart, Daniel Baggenstos, Jennie L. Thomas, Rachael H. Rhodes, Michael Sigl, Division of Hydrologic Sciences, Desert Research Institute (DRI), School of Earth and Environmental Sciences [University St Andrews], University of St Andrews [Scotland], New Mexico Institute of Mining and Technology [New Mexico Tech] (NMT), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Department of Chemistry and Biochemistry [Brookings], South Dakota State University (SDSTATE), Department of Earth and Space Sciences [Seattle], University of Washington [Seattle], Centre for Atmospheric Science [Cambridge, UK], University of Cambridge [UK] (CAM), Department of Earth System Science [Irvine] (ESS), University of California [Irvine] (UCI), Division of Earth and Ecosystem Sciences (DEES), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Department of Earth Sciences [Cambridge, UK], Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Arienzo, Monica M [0000-0003-3444-9810], Severinghaus, Jeffrey P [0000-0001-8883-3119], Apollo - University of Cambridge Repository, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry, Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), University of California [Irvine] (UC Irvine), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], and University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)
- Subjects
010504 meteorology & atmospheric sciences ,aerosol ,Climate change ,Antarctic ice sheet ,010502 geochemistry & geophysics ,Atmospheric sciences ,deglaciation ,01 natural sciences ,Ice core ,Paleoclimatology ,SDG 13 - Climate Action ,Deglaciation ,[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology ,climate ,R2C ,0105 earth and related environmental sciences ,volcanism ,GE ,Multidisciplinary ,DAS ,Westerlies ,Ozone depletion ,ozone ,13. Climate action ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,Climatology ,Physical Sciences ,Abrupt climate change ,BDC ,SDG 12 - Responsible Consumption and Production ,Geology ,GE Environmental Sciences - Abstract
Significance: Cold and dry glacial-state climate conditions persisted in the Southern Hemisphere until approximately 17.7 ka, when paleoclimate records show a largely unexplained sharp, nearly synchronous acceleration in deglaciation. Detailed measurements in Antarctic ice cores document exactly at that time a unique, ∼192-y series of massive halogen-rich volcanic eruptions geochemically attributed to Mount Takahe in West Antarctica. Rather than a coincidence, we postulate that halogen-catalyzed stratospheric ozone depletion over Antarctica triggered large-scale atmospheric circulation and hydroclimate changes similar to the modern Antarctic ozone hole, explaining the synchronicity and abruptness of accelerated Southern Hemisphere deglaciation. Abstract: Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found >2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics—similar to those associated with modern stratospheric ozone depletion over Antarctica—plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka.
- Published
- 2017
10. Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene
- Author
-
Olivia J. Maselli, John C. Priscu, Mark C. Greenwood, Mackenzie M. Grieman, Pamela A. Santibáñez, Joseph R. McConnell, and Eric S. Saltzman
- Subjects
0301 basic medicine ,Time Factors ,010504 meteorology & atmospheric sciences ,030106 microbiology ,Antarctic ice sheet ,Antarctic Regions ,01 natural sciences ,03 medical and health sciences ,Ice core ,Deglaciation ,Environmental Chemistry ,Ice Cover ,Meltwater ,Holocene ,History, Ancient ,0105 earth and related environmental sciences ,General Environmental Science ,Global and Planetary Change ,Ecology ,Bacteria ,Sodium ,Last Glacial Maximum ,15. Life on land ,Models, Theoretical ,Archaea ,Deposition (aerosol physics) ,13. Climate action ,Polar ,Physical geography ,Geology - Abstract
We present the first long-term, highly resolved prokaryotic cell concentration record obtained from a polar ice core. This record, obtained from the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core, spanned from the Last Glacial Maximum (LGM) to the early Holocene (EH) and showed distinct fluctuations in prokaryotic cell concentration coincident with major climatic states. The time series also revealed a ~1,500-year periodicity with greater amplitude during the Last Deglaciation (LDG). Higher prokaryotic cell concentration and lower variability occurred during the LGM and EH than during the LDG. A sevenfold decrease in prokaryotic cell concentration coincided with the LGM/LDG transition and the global 19 ka meltwater pulse. Statistical models revealed significant relationships between the prokaryotic cell record and tracers of both marine (sea-salt sodium [ssNa]) and burning emissions (black carbon [BC]). Collectively, these models, together with visual observations and methanosulfidic acid (MSA) measurements, indicated that the temporal variability in concentration of airborne prokaryotic cells reflected changes in marine/sea-ice regional environments of the WAIS. Our data revealed that variations in source and transport were the most likely processes producing the significant temporal variations in WD prokaryotic cell concentrations. This record provided strong evidence that airborne prokaryotic cell deposition differed during the LGM, LDG, and EH, and that these changes in cell densities could be explained by different environmental conditions during each of these climatic periods. Our observations provide the first ice-core time series evidence for a prokaryotic response to long-term climatic and environmental processes.
- Published
- 2017
11. Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core
- Author
-
Simon Schüpbach, Joseph R. McConnell, Piero Zennaro, Andrea Spolaor, Matteo Borrotti, Natalie Kehrwald, Paul Vallelonga, Elena Barbaro, Andrea Gambaro, R. Zangrando, Olivia J. Maselli, Carlo Barbante, Jennifer R. Marlon, Daiana Leuenberger, Zennaro, P, Kehrwald, N, Mcconnell, J, Schüpbach, S, Maselli, O, Marlon, J, Vallelonga, P, Leuenberger, D, Zangrando, R, Spolaor, A, Borrotti, M, Barbaro, E, Gambaro, A, and Barbante, C
- Subjects
biomass burning ,LAST MILLENNIUM ,010504 meteorology & atmospheric sciences ,530 Physics ,aerosol ,Stratigraphy ,lcsh:Environmental protection ,drought ,010501 environmental sciences ,01 natural sciences ,Carbon cycle ,VEGETATION EMISSIONS ,chemistry.chemical_compound ,Neem ice core ,WESTERN UNITED-STATES, LONG-RANGE TRANSPORT, BLACK CARBON, MASS-SPECTROMETRY, LAST MILLENNIUM, VEGETATION EMISSIONS, MOLECULAR TRACERS, CARBOXYLIC-ACIDS, HOLOCENE CLIMATE, ORGANIC AEROSOLS ,Ice core ,lcsh:Environmental pollution ,East Asian Monsoon ,Settore CHIM/01 - Chimica Analitica ,lcsh:TD169-171.8 ,boreal forest ,LONG-RANGE TRANSPORT ,lcsh:Environmental sciences ,CARBOXYLIC-ACIDS ,HOLOCENE CLIMATE ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,Eemian ,Levoglucosan ,Taiga ,Paleontology ,MOLECULAR TRACERS ,MASS-SPECTROMETRY ,WESTERN UNITED-STATES ,15. Life on land ,ORGANIC AEROSOLS ,fire history ,chemistry ,Boreal ,13. Climate action ,Climatology ,Greenhouse gas ,BLACK CARBON ,lcsh:TD172-193.5 ,Environmental science ,Physical geography ,forest fire - Abstract
Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales spanning millennia, and are thus useful to examine the role of fire in the carbon cycle and climate system. Here we use the specific biomarker levoglucosan together with black carbon and ammonium concentrations from the North Greenland Eemian (NEEM) ice cores (77.49° N, 51.2° W; 2480 m a.s.l) over the past 2000 years to infer changes in boreal fire activity. Increases in boreal fire activity over the periods 1000–1300 CE and decreases during 700–900 CE coincide with high-latitude NH temperature changes. Levoglucosan concentrations in the NEEM ice cores peak between 1500 and 1700 CE, and most levoglucosan spikes coincide with the most extensive central and northern Asian droughts of the past millennium. Many of these multi-annual droughts are caused by Asian monsoon failures, thus suggesting a connection between low- and high-latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the Greenland Ice Cap. During major fire events, however, isotopic analyses of dust, back trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.
- Published
- 2014
12. Seasonally resolved ice core records from West Antarctica indicate a sea ice source of sea-salt aerosol and a biomass burning source of ammonium
- Author
-
Joseph R. McConnell, Matthew J. Evans, A. S. Criscitiello, Sarah B. Das, Daniel R. Pasteris, Michael Sigl, Olivia J. Maselli, and Lawrence Layman
- Subjects
Atmospheric Science ,geography ,geography.geographical_feature_category ,Antarctic sea ice ,Snow ,Arctic ice pack ,Aerosol ,Geophysics ,Oceanography ,Ice core ,Space and Planetary Science ,Earth and Planetary Sciences (miscellaneous) ,Sea ice ,Cryosphere ,Environmental science ,Sea salt aerosol - Abstract
The sources and transport pathways of aerosol species in Antarctica remain uncertain, partly due to limited seasonally resolved data from the harsh environment. Here, we examine the seasonal cycles of major ions in three high-accumulation West Antarctic ice cores for new information regarding the origin of aerosol species. A new method for continuous acidity measurement in ice cores is exploited to provide a comprehensive, charge-balance approach to assessing the major non-sea-salt (nss) species. The average nss-anion composition is 41% sulfate (SO42−), 36% nitrate (NO3−), 15% excess-chloride (ExCl−), and 8% methanesulfonic acid (MSA). Approximately 2% of the acid-anion content is neutralized by ammonium (NH4+), and the remainder is balanced by the acidity (Acy ≈ H+ − HCO3−). The annual cycle of NO3− shows a primary peak in summer and a secondary peak in late winter/spring that are consistent with previous air and snow studies in Antarctica. The origin of these peaks remains uncertain, however, and is an area of active research. A high correlation between NH4+ and black carbon (BC) suggests that a major source of NH4+ is midlatitude biomass burning rather than marine biomass decay, as previously assumed. The annual peak in excess chloride (ExCl−) coincides with the late-winter maximum in sea ice extent. Wintertime ExCl− is correlated with offshore sea ice concentrations and inversely correlated with temperature from nearby Byrd station. These observations suggest that the winter peak in ExCl− is an expression of fractionated sea-salt aerosol and that sea ice is therefore a major source of sea-salt aerosol in the region.
- Published
- 2014
13. Insights from Antarctica on volcanic forcing during the Common Era
- Author
-
Mirko Severi, Ross Edwards, Yuko Motizuki, Sarah B. Das, Sepp Kipfstuhl, Matthew Toohey, Joseph R. McConnell, Hideaki Motoyama, Mark A. J. Curran, Kenji Kawamura, Daniel R. Pasteris, Lawrence Layman, Elisabeth Isaksson, Kirstin Krüger, Olivia J. Maselli, and Michael Sigl
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Antarctic ice sheet ,Forcing (mathematics) ,Environmental Science (miscellaneous) ,010502 geochemistry & geophysics ,01 natural sciences ,Glacier mass balance ,Deposition (aerosol physics) ,Ice core ,Volcano ,13. Climate action ,Climatology ,Climate sensitivity ,Cryosphere ,Social Sciences (miscellaneous) ,Geology ,0105 earth and related environmental sciences - Abstract
Assessments of climate sensitivity to projected greenhouse gas concentrations underpin environmental policy decisions, with such assessments often based on model simulations of climate during recent centuries and millennia1, 2, 3. These simulations depend critically on accurate records of past aerosol forcing from global-scale volcanic eruptions, reconstructed from measurements of sulphate deposition in ice cores4, 5, 6. Non-uniform transport and deposition of volcanic fallout mean that multiple records from a wide array of ice cores must be combined to create accurate reconstructions. Here we re-evaluated the record of volcanic sulphate deposition using a much more extensive array of Antarctic ice cores. In our new reconstruction, many additional records have been added and dating of previously published records corrected through precise synchronization to the annually dated West Antarctic Ice Sheet Divide ice core7, improving and extending the record throughout the Common Era. Whereas agreement with existing reconstructions is excellent after 1500, we found a substantially different history of volcanic aerosol deposition before 1500; for example, global aerosol forcing values from some of the largest eruptions (for example, 1257 and 1458) previously were overestimated by 20–30% and others underestimated by 20–50%.
- Published
- 2014
14. Comparison of water isotope-ratio determinations using two cavity ring-down instruments and classical mass spectrometry in continuous ice-core analysis
- Author
-
Joseph R. McConnell, Olivia J. Maselli, Hanno Meyer, Diedrich Fritzsche, and Lawrence Layman
- Subjects
Oxygen-18 ,Accuracy and precision ,010504 meteorology & atmospheric sciences ,Resolution (mass spectrometry) ,Isotope ,Chemistry ,Spectrum Analysis ,Analytical chemistry ,Water ,Flash evaporation ,010501 environmental sciences ,Deuterium ,Mass spectrometry ,01 natural sciences ,Mass Spectrometry ,Russia ,Inorganic Chemistry ,Ice core ,Ring down ,Environmental Chemistry ,Ice Cover ,Environmental Monitoring ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
We present a detailed comparison between subsequent versions of commercially available wavelength-scanned cavity ring-down water isotope analysers (L2120-i and L2130-i, Picarro Inc.). The analysers are used in parallel in a continuous mode by adaption of a low-volume flash evaporation module. Application of the analysers to ice-core analysis is assessed by comparison between continuous water isotope measurements of a glacial ice-core from Severnaya Zemlya with discrete isotope-ratio mass spectrometry measurements performed on parallel samples from the same ice-core. The great advances between instrument versions, particularly in the measurement of δ(2)H, allow the continuous technique to achieve the same high level of accuracy and precision obtained using traditional isotope spectrometry techniques in a fraction of the experiment time. However, when applied to continuous ice-core measurements, increased integration times result in a compromise of the achievable depth resolution of the ice-core records.
- Published
- 2013
15. Onset of deglacial warming in West Antarctica driven by local orbital forcing
- Author
-
Bruce H. Vaughn, Xianfeng Wang, David G. Ferris, Bradley R. Markle, Edward J. Brook, Kendrick C. Taylor, Howard Conway, Anais Orsi, Nicolai B. Mortensen, Edwin D. Waddington, Joseph R. McConnell, Kenneth C. McGwire, Peter Neff, William P. Mason, James E. Lee, Qinghua Ding, Eric J. Steig, G. J. Wong, Tyler J. Fudge, Geoffrey M. Hargreaves, Michael Sigl, Jeffrey P. Severinghaus, Joan J. Fitzpatrick, Todd Sowers, Logan Mitchell, Olivia J. Maselli, Gary D. Clow, J. S. Edwards, John M. Fegyveresi, Richard B. Alley, Jay A. Johnson, Trevor Popp, Donald E. Voigt, Jihong Cole-Dai, M. K. Spencer, Hai Cheng, James W. C. White, Kurt M. Cuffey, R. Lawrence Edwards, Ross Edwards, Spruce W. Schoenemann, and Andrew J. Schauer
- Subjects
Insolation ,Time Factors ,Orbital forcing ,Oceans and Seas ,Antarctic Regions ,Oxygen Isotopes ,Sodium Chloride ,Global Warming ,Ice core ,Snow ,Water Movements ,Ice Cover ,Seawater ,Southern Hemisphere ,History, Ancient ,geography ,Multidisciplinary ,geography.geographical_feature_category ,Atmosphere ,Temperature ,Carbon Dioxide ,Models, Theoretical ,Ice-sheet model ,Oceanography ,Abrupt climate change ,Ice sheet ,Methane ,Geology ,Chronology - Abstract
The cause of warming in the Southern Hemisphere during the most recent deglaciation remains a matter of debate. Hypotheses for a Northern Hemisphere trigger, through oceanic redistributions of heat, are based in part on the abrupt onset of warming seen in East Antarctic ice cores and dated to 18,000 years ago, which is several thousand years after high-latitude Northern Hemisphere summer insolation intensity began increasing from its minimum, approximately 24,000 years ago. An alternative explanation is that local solar insolation changes cause the Southern Hemisphere to warm independently. Here we present results from a new, annually resolved ice-core record from West Antarctica that reconciles these two views. The records show that 18,000 years ago snow accumulation in West Antarctica began increasing, coincident with increasing carbon dioxide concentrations, warming in East Antarctica and cooling in the Northern Hemisphere associated with an abrupt decrease in Atlantic meridional overturning circulation. However, significant warming in West Antarctica began at least 2,000 years earlier. Circum-Antarctic sea-ice decline, driven by increasing local insolation, is the likely cause of this warming. The marine-influenced West Antarctic records suggest a more active role for the Southern Ocean in the onset of deglaciation than is inferred from ice cores in the East Antarctic interior, which are largely isolated from sea-ice changes.
- Published
- 2013
16. A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years
- Author
-
Kenneth C. McGwire, Joseph R. McConnell, Daniel R. Pasteris, Ross Edwards, Lawrence Layman, Robert Mulvaney, Sepp Kipfstuhl, Dorthe Dahl-Jensen, Olivia J. Maselli, Bo Møllesøe Vinther, Jørgen Peder Steffensen, and Michael Sigl
- Subjects
Atmospheric Science ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Volcanism ,Radiative forcing ,010502 geochemistry & geophysics ,01 natural sciences ,Proxy (climate) ,Geophysics ,Ice core ,Volcano ,13. Climate action ,Space and Planetary Science ,Climatology ,Paleoclimatology ,Earth and Planetary Sciences (miscellaneous) ,Cryosphere ,Ice sheet ,Geology ,0105 earth and related environmental sciences - Abstract
Volcanism is a natural climate forcing causing short-term variations in temperatures. Histories of volcanic eruptions are needed to quantify their role in climate variability and assess human impacts. We present two new seasonally resolved, annually dated non-sea-salt sulfur records from polar ice cores - WAIS Divide (WDC06A) from West Antarctica spanning 408 B.C.E. to 2003 C.E. and NEEM (NEEM-2011-S1) from Greenland spanning 78 to 1997 C.E. - both analyzed using high-resolution continuous flow analysis coupled to two mass spectrometers. The high dating accuracy allowed placing the large bi-hemispheric deposition event ascribed to the eruption of Kuwae in Vanuatu (previously thought to be 1452/1453 C.E. and used as a tie-point in ice core dating) into the year 1458/1459 C.E. This new age is consistent with an independent ice core timescale from Law Dome and explains an apparent delayed response in tree rings to this volcanic event. A second volcanic event is detected in 1453 C.E. in both ice cores. We show for the first time ice core signals in Greenland and Antarctica from the strong eruption of Taupo in New Zealand in 232 C.E. In total, 133 volcanic events were extracted from WDC06A and 138 from NEEM-2011-S1, with 50 ice core signals - predominantly from tropical source volcanoes - identified simultaneously in both records. We assess the effect of large bipolar events on temperature-sensitive tree ring proxies. These two new volcanic records, synchronized with available ice core records to account for spatial variability in sulfate deposition, provide a basis for improving existing time series of volcanic forcing.
- Published
- 2013
17. The WAIS Divide deep ice core WD2014 chronology – Part 2: Annual-layer counting (0–31 ka BP)
- Author
-
Daniel R. Pasteris, Ken C. Taylor, Nelia W. Dunbar, David G. Ferris, Lei Geng, Edward J. Brook, Raimund Muscheler, Lawrence Layman, Joseph R. McConnell, Olivia J. Maselli, M. M. Bisiaux, Thomas E. Woodruff, Jihong Cole-Dai, Todd Sowers, Kees C. Welten, Nels Iverson, Florian Adolphi, Kunihiko Nishiizumi, Tyler J. Fudge, B. G. Koffman, Christo Buizert, Michael Sigl, Marc W. Caffee, Kenneth C. McGwire, Ross Edwards, Mai Winstrup, Rachael H. Rhodes, Paul Scherrer Institute (PSI), Desert Research Institute (DRI), University of Washington [Seattle], Department of Chemistry and Biochemistry [Brookings], South Dakota State University (SDSTATE), Dartmouth College [Hanover], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Purdue University [West Lafayette], Department of Geology [Lund], Lund University [Lund], College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), New Mexico Institute of Mining and Technology [New Mexico Tech] (NMT), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Earth and Environmental Systems Institute (EESI), Pennsylvania State University (Penn State), Penn State System-Penn State System, Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
010506 paleontology ,010504 meteorology & atmospheric sciences ,Stratigraphy ,lcsh:Environmental protection ,Antarctic ice sheet ,F800 ,Mineral dust ,01 natural sciences ,Ice core ,lcsh:Environmental pollution ,lcsh:TD169-171.8 ,Glacial period ,Southern Hemisphere ,Holocene ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,Paleontology ,13. Climate action ,Climatology ,[SDE]Environmental Sciences ,lcsh:TD172-193.5 ,Abrupt climate change ,Geology ,Chronology - Abstract
International audience; We present the WD2014 chronology for the upper part (0–2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposi-tion of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cos-mogenic isotope records of 10 Be from WAIS Divide and 14 C for IntCal13 demonstrated that WD2014 was consistently accurate to better than 0.5 % of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated that WD2014 had an accuracy of better than 1 % of the age at three abrupt climate change events between 27 and 31 ka. WD2014 has consistently younger ages than Green-land ice core chronologies during most of the Holocene. For Published by Copernicus Publications on behalf of the European Geosciences Union. 770 M. Sigl et al.: The WAIS Divide deep ice core WD2014 chronology the Younger Dryas–Preboreal transition (11.595 ka; 24 years younger) and the Bølling–Allerød Warming (14.621 ka; 7 years younger), WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high-quality proxies of volcanism, solar activity , atmospheric mineral dust, and atmospheric methane concentrations.
- Published
- 2016
18. The dynamics of evaporation from a liquid surface
- Author
-
Jason R. Gascooke, Warren D. Lawrance, Mark A. Buntine, and Olivia J. Maselli
- Subjects
Chemistry ,Evaporation ,General Physics and Astronomy ,Thermodynamics ,Rotational temperature ,Molecular physics ,Rotational energy ,symbols.namesake ,Molecular vibration ,Boltzmann constant ,Vibrational energy relaxation ,symbols ,Relaxation (physics) ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Ground state - Abstract
We explore the collisional energy transfer dynamics of benzene molecules spontaneously evaporating from an in vacuo water–ethanol liquid beam. We find that rotations are cooled significantly more than the lowest-energy vibrational modes, while the rotational energy distributions are Boltzmann. Within experimental uncertainty, the rotational temperatures of vibrationally-excited evaporating molecules are the same as the ground state. Collision-induced gas phase energy transfer measurements reveal that benzene undergoes fast rotational relaxation, from which we deduce that the rotational temperature measured in the evaporation experiments (200–230 K) is an indication of the translational energy of the evaporate. Conversely, vibrational relaxation of the high frequency mode, ν6, is very inefficient, suggesting that the ν6 temperature (260–270 K) is an indication of the liquid surface temperature. Modelling of the relaxation dynamics by both ‘temperature gap’ and ‘Master Equation’ approaches indicates that the equivalent of 150–260 hard-sphere collisions occur during the transition from liquid to vacuum.
- Published
- 2011
19. Benzene Internal Energy Distributions Following Spontaneous Evaporation from a Water−Ethanol Solution
- Author
-
Jason R. Gascooke, Olivia J. Maselli, Mark A. Buntine, and Warren D. Lawrance
- Subjects
X-ray spectroscopy ,Ethanol ,Vibrational energy ,Internal energy ,Analytical chemistry ,Evaporation ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Soft Condensed Matter ,Physics::Fluid Dynamics ,Molecular dynamics ,chemistry.chemical_compound ,General Energy ,chemistry ,Physics::Atomic and Molecular Clusters ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Spectroscopy ,Benzene ,Physics::Atmospheric and Oceanic Physics - Abstract
We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water−ethanol solution. We ...
- Published
- 2008
20. Paleoclimate. Enhanced tropical methane production in response to iceberg discharge in the North Atlantic
- Author
-
Rachael H, Rhodes, Edward J, Brook, John C H, Chiang, Thomas, Blunier, Olivia J, Maselli, Joseph R, McConnell, Daniele, Romanini, and Jeffrey P, Severinghaus
- Abstract
The causal mechanisms responsible for the abrupt climate changes of the Last Glacial Period remain unclear. One major difficulty is dating ice-rafted debris deposits associated with Heinrich events: Extensive iceberg influxes into the North Atlantic Ocean linked to global impacts on climate and biogeochemistry. In a new ice core record of atmospheric methane with ultrahigh temporal resolution, we find abrupt methane increases within Heinrich stadials 1, 2, 4, and 5 that, uniquely, have no counterparts in Greenland temperature proxies. Using a heuristic model of tropical rainfall distribution, we propose that Hudson Strait Heinrich events caused rainfall intensification over Southern Hemisphere land areas, thereby producing excess methane in tropical wetlands. Our findings suggest that the climatic impacts of Heinrich events persisted for 740 to 1520 years.
- Published
- 2015
21. Enhanced tropical methane production in response to iceberg discharge in the North Atlantic
- Author
-
Thomas Blunier, Daniele Romanini, Edward J. Brook, John C. H. Chiang, Olivia J. Maselli, Jeffrey P. Severinghaus, Joseph R. McConnell, Rachael H. Rhodes, Université Paris-Est (UPE), Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), LAsers, Molécules et Environnement (LAME-LIPhy), Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères] (LIPhy), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), and University of California-University of California
- Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics] ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,Atmospheric methane ,Climate change ,Biogeochemistry ,010502 geochemistry & geophysics ,01 natural sciences ,Iceberg ,Oceanography ,Ice core ,13. Climate action ,Abrupt climate change ,Environmental science ,Glacial period ,Stadial ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
The tropical impact of iceberg armadas The massive discharges of icebergs from the Greenland ice sheet during the Last Glacial Period are called Heinrich events. But did Heinrich events cause abrupt climate change, or were they a product of it? Methane levels represent a proxy for climate, because methane production increases mostly due to wetter conditions in the tropics. Rhodes et al. report a highly resolved record of atmospheric methane concentrations, derived from an ice core from Antarctica. Methane levels varied—i.e., the tropical climate changed—in response to cooling in the Northern Hemisphere caused by Heinrich events. Science , this issue p. 1016
- Published
- 2015
22. Precise interpolar phasing of abrupt climate change during the last ice age
- Author
-
Peter Neff, Thomas E. Woodruff, Nelia W. Dunbar, Shaun A. Marcott, Eric J. Steig, Joel B Pedro, Chris J. Gibson, Kristina Slawny, R. C. Bay, Edward J. Brook, Howard Conway, B. G. Koffman, Daniel Baggenstos, Joan J. Fitzpatrick, Joseph M. Souney, Nicolai B. Mortensen, Andrew J. Schauer, Stephanie Gregory, Erin C. Pettit, Richard B. Alley, Spruce W. Schoenemann, Richard M. Nunn, Bruce H. Vaughn, Tyler R. Jones, Michael Sigl, Alexander J. Shturmakov, John M. Fegyveresi, Mai Winstrup, Mark S. Twickler, Todd Sowers, Nels Iverson, Karl J. Kreutz, James W. C. White, Kunihiko Nishiizumi, Kurt M. Cuffey, Geoffrey M. Hargreaves, T. K. Bauska, Edwin D. Waddington, Jinho Ahn, Matthew J. Kippenhan, Bradley R. Markle, P. Buford Price, Vasileios Gkinis, Tanner W. Kuhl, Nathan Chellman, J. S. Edwards, Logan Mitchell, G. J. Wong, Anthony W. Wendricks, Joshua J. Goetz, Kees C. Welten, Rachael H. Rhodes, Olivia J. Maselli, Tyler J. Fudge, Gary D. Clow, Jihong Cole-Dai, Jeffrey P. Severinghaus, Brian B. Bencivengo, Joseph R. McConnell, Charles R. Bentley, Julia Rosen, Kenneth C. McGwire, Eric D. Cravens, Betty Adrian, Mary R. Albert, D. G. Ferris, John C. Priscu, M. K. Spencer, Daniel R. Pasteris, M. Kalk, Donald A. Lebar, Anais Orsi, James E. Lee, Jay A. Johnson, Paul J. Sendelbach, Donald E. Voigt, Christo Buizert, Kendrick C. Taylor, Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Department of Chemistry and Biochemistry [Brookings], South Dakota State University (SDSTATE), New Mexico Institute of Mining and Technology [New Mexico Tech] (NMT), University of Michigan [Ann Arbor], University of Michigan System, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Climate Change Institute [Orono] (CCI), University of Maine, Johannes Gutenberg - Universität Mainz (JGU), University of Washington [Seattle], Desert Research Institute (DRI), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratory of Radio- and Environmental Chemistry [Villigen], Paul Scherrer Institute (PSI), Earth and Environmental Systems Institute (EESI), Pennsylvania State University (Penn State), Penn State System-Penn State System, Purdue University [West Lafayette], Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), University of California [Berkeley] (UC Berkeley), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,010506 paleontology ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,fungi ,Northern Hemisphere ,01 natural sciences ,Latitude ,Ice-sheet model ,Oceanography ,Ice core ,13. Climate action ,Climatology ,Ice age ,Abrupt climate change ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,Southern Hemisphere ,ComputingMilieux_MISCELLANEOUS ,Geology ,0105 earth and related environmental sciences - Abstract
The last glacial period exhibited abrupt Dansgaard-Oeschger climatic oscillations, evidence of which is preserved in a variety of Northern Hemisphere palaeoclimate archives. Ice cores show that Antarctica cooled during the warm phases of the Greenland Dansgaard-Oeschger cycle and vice versa, suggesting an interhemispheric redistribution of heat through a mechanism called the bipolar seesaw. Variations in the Atlantic meridional overturning circulation (AMOC) strength are thought to have been important, but much uncertainty remains regarding the dynamics and trigger of these abrupt events. Key information is contained in the relative phasing of hemispheric climate variations, yet the large, poorly constrained difference between gas age and ice age and the relatively low resolution of methane records from Antarctic ice cores have so far precluded methane-based synchronization at the required sub-centennial precision. Here we use a recently drilled high-accumulation Antarctic ice core to show that, on average, abrupt Greenland warming leads the corresponding Antarctic cooling onset by 218 ± 92 years (2σ) for Dansgaard-Oeschger events, including the Bølling event; Greenland cooling leads the corresponding onset of Antarctic warming by 208 ± 96 years. Our results demonstrate a north-to-south directionality of the abrupt climatic signal, which is propagated to the Southern Hemisphere high latitudes by oceanic rather than atmospheric processes. The similar interpolar phasing of warming and cooling transitions suggests that the transfer time of the climatic signal is independent of the AMOC background state. Our findings confirm a central role for ocean circulation in the bipolar seesaw and provide clear criteria for assessing hypotheses and model simulations of Dansgaard-Oeschger dynamics.
- Published
- 2014
23. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today
- Author
-
Mark A. J. Curran, Paul Vallelonga, Helgard Anschütz, Sarah B. Das, Thomas Neumann, Joseph R. McConnell, Ross Edwards, Michael Sigl, Sepp Kipfstuhl, Lawrence Layman, Elizabeth R. Thomas, Olivia J. Maselli, and Roger C. Bales
- Subjects
Pollution ,History ,Atmospheric circulation ,media_common.quotation_subject ,Earth science ,Antarctic Regions ,Chemical ,History, 21st Century ,Mining ,Deposition (geology) ,Article ,Isotopic signature ,Ice core ,Faculty of Science ,Humans ,Ecosystem ,Water Pollutants ,media_common ,19th Century ,Multidisciplinary ,Lead (sea ice) ,Ice ,Australia ,History, 19th Century ,History, 20th Century ,21st Century ,Lead isotopes ,20th Century ,Other Physical Sciences ,Sea surface temperature ,Lead ,13. Climate action ,Antarctica ,Environmental science ,Biochemistry and Cell Biology ,Environmental Pollution ,Water Pollutants, Chemical - Abstract
Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20 th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19 th century and remains a significant source today. An estimated 660 €...t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21 st century.
- Published
- 2014
24. Fire in ice: two millennia of Northern Hemisphere fire history from the Greenland NEEM ice core
- Author
-
Elena Barbaro, Paul Vallelonga, Natalie Kehrwald, Andrea Gambaro, Piero Zennaro, Simon Schüpbach, R. Zangrando, Jennifer R. Marlon, Joseph R. McConnell, Andrea Spolaor, Olivia J. Maselli, Daiana Leuenberger, Carlo Barbante, and Matteo Borrotti
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Northern Hemisphere ,15. Life on land ,010502 geochemistry & geophysics ,01 natural sciences ,Ice core ,N/A ,13. Climate action ,Climatology ,Ice age ,Cryosphere ,Ice sheet ,Fire history ,Geology ,0105 earth and related environmental sciences - Abstract
Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales, but there remains a need for broad-scale fire proxies that span millennia in order to understand the role of fire in the carbon cycle and climate system. We use the specific biomarker levoglucosan, and multi-source black carbon and ammonium concentrations to reconstruct fire activity from the North Greenland Eemian (NEEM) ice cores (77.49° N; 51.2° W, 2480 m a.s.l.) over the past 2000 years. Increases in boreal fire activity (1000–1300 CE and 1500–1700 CE) over multi-decadal timescales coincide with the most extensive central and northern Asian droughts of the past two millennia. The NEEM biomass burning tracers coincide with temperature changes throughout much of the past 2000 years except for during the extreme droughts, when precipitation changes are the dominant factor. Many of these multi-annual droughts are caused by monsoon failures, thus suggesting a connection between low and high latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the NEEM camp. During major fire events, however, isotopic analyses of dust, back-trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.
- Published
- 2014
- Full Text
- View/download PDF
25. Translational and rotational energy content of benzene molecules IR-desorbed from an in vacuo liquid surface
- Author
-
Mark A. Buntine, Jason R. Gascooke, Makoto Shoji, and Olivia J. Maselli
- Subjects
chemistry.chemical_compound ,Number density ,Chemistry ,Absorption band ,Desorption ,Analytical chemistry ,Evaporation ,General Physics and Astronomy ,Vibronic spectroscopy ,Rotational temperature ,Physical and Theoretical Chemistry ,Benzene ,Rotational energy - Abstract
Benzene molecules were desorbed from an in vacuo aqueous liquid beam by direct irradiation of the beam with an IR laser tuned to the 2.85 μm absorption band of water. Spectroscopic interrogation of the desorbed benzene molecules was performed via 1 + 1 Resonance-Enhanced Multi-photon Ionisation (REMPI). Rotational contour analyses of the 610 vibronic transition of benzene were performed to determine the rotational temperature of those molecules ejected during the desorption event. At the peak of the desorption plume density, the rotational temperatures were found to be up to ∼100 K lower than that recorded for molecules spontaneously evaporating from the liquid surface. At longer IR-UV laser delay times the benzene rotational temperatures are found to return to those observed following spontaneous evaporation. No evidence of IR desorbed neutral or cationic benzene-containing clusters was observed. However, ionic clusters were observed to be formed after REMPI of the benzene monomer. Analysis of the benzene intensity and that of post-REMPI formed clusters as a function of IR-UV delay shows that number density and local translational temperature vary along the desorption plume.
- Published
- 2012
26. Boreal fire records in Northern Hemisphere ice cores: a review
- Author
-
Nathan Chellman, Joseph R. McConnell, Simon Schüpbach, P. Place, Mike D. Flannigan, Eric W. Wolff, Olivia J. Maselli, Daiana Leuenberger, Hubertus Fischer, Susanne Preunkert, Monica M. Arienzo, Michel Legrand, and Michael Sigl
- Subjects
010504 meteorology & atmospheric sciences ,530 Physics ,lcsh:Environmental protection ,Stratigraphy ,sub-01 ,Greenland ice sheet ,010502 geochemistry & geophysics ,01 natural sciences ,chemistry.chemical_compound ,lcsh:Environmental pollution ,Ice core ,Cryosphere ,lcsh:TD169-171.8 ,lcsh:Environmental sciences ,Holocene ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Levoglucosan ,Paleontology ,Glacier ,15. Life on land ,Ice-sheet model ,Boreal ,chemistry ,13. Climate action ,Climatology ,lcsh:TD172-193.5 ,Environmental science ,Physical geography - Abstract
Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. pre-industrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species – potassium, nitrate, and carboxylates (except formate) – is complicated by either post-depositional effects or existence of large non-biomass-burning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of high-resolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region.
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.